


Claiming The Beast

by PenguinKiwis



Category: Fullmetal Alchemist - All Media Types, Fullmetal Alchemist: Brotherhood & Manga
Genre: Abandoned Work - Unfinished and Discontinued, Alpha/Beta/Omega Dynamics, Alternate Universe, Alternate Universe - Canon Divergence, Anal Fingering, Anal Sex, Because of Reasons, Blood and Gore, Blood and Injury, Kimblee Switches Sides AU, Kinda, M/M, Not Beta Read, Not Beta Read We Die Like Maes, Not Suitable/Safe For Work, Porn With Plot, Smut, headcanons, i guess, is that too soon? Its too soon.
Language: English
Status: Completed
Published: 2020-10-25
Updated: 2020-10-29
Packaged: 2021-03-09 07:15:00
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 8,742
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27199694
Author URL: https://archiveofourown.org/users/PenguinKiwis/pseuds/PenguinKiwis
Summary: Kimblee’s pre heat hits hard and unexpected in an inopportune time. That might not be such a bad thing if it means he defects from the Homunculi.HeinKim because I’m a moron.
Relationships: Heinkel/Zolf J. Kimblee (Fullmetal Alchemist)
Comments: 10
Kudos: 16





	1. Chapter 1

**Author's Note:**

> "Shouldn't you be working on Breath of the Void/Red Dragon/ more of Jee's Misadventures?" I mean yeah, but I'm avoiding work and some moron (me) found that Kimblee is the FMA town bike and this is my life now. Also I thrive off of the fact that Kimblee is "tall" but Heinkel is a giant.

**Summary for the Chapter:**

> Kimblee’s pre-heat hits hard and unexpected at an inopportune time. That might not be such a bad thing if it means he defects from the Homunculi.
> 
> HeinKim because I’m a moron.

**Notes for the Chapter:**

> "Shouldn't you be working on Breath of the Void/Red Dragon/ more of Jee's Misadventures?" I mean yeah, but I'm avoiding work and some moron (me) found that Kimblee is the FMA town bike and this is my life now. Also I thrive off of the fact that Kimblee is "tall" but Heinkel is a giant.

His internal and biological clock was off and would probably continue to be off for a few more months. Things like that happened, he supposed, if one was locked in a dark and windowless cell for six years— mostly, getting released for a routinely clean up and other hygiene requirements didn’t count, fluorescent lights didn’t keep one in the know of what time or what day it was.

He was just lucky that for six years the state decided to be _merciful_ with how they handled the, ahem, monthly issue, he had. If being merciful counted as drugging him with suppressants and a high dose of sedatives for a week.

Of course, fate wouldn’t be so kind to him now, it seemed.

Zolf J. Kimblee had felt it creeping up on him since he had first arrived at the northern wall of Briggs, but his body was all out of sorts and it had held off for much longer than usual. He had been a fool to simply brush off the sharp tendrils of pain that clawed at his gut, and the thudding of his blood in his ears and heart any time Captain Buccaneer or Major Miles got _near_ him. 

And he had been even more of a fool to brush it off to the side _again_ when the four Chimeras arrived.

He ignored the sharp pains when Scar reappeared with the Rockbell girl as a hostage (didn’t she know that it was dangerous to wander around like that? How the hell did she even get in Scar's clutches anyway?) and he had pushed the sharp pinpricks of pain to the side when rage had overtaken him at Scar’s taunts.

He had ignored the intense increase in temperature when he exited the open cold while the Lion and Gorilla Chimeras— Heinkel and… Darius, he was certain that was the other’s name— attacked Edward Elric after he kicked up a barrier of snow. He could ignore it while he fought the boy, brushing off the aching feeling and painful stabs as just being a part of him being rusty and not used to battle yet again. 

But it all came crumbling down when the Fullmetal Alchemist slashed his palm open in an attempt to stop him from activating his Alchemy. 

Zolf staggered back, panting just a bit as the gnawing pain and heat in his stomach became too prominent to pretend that it was just his body being out of sorts. His Pre-heat had decided to rear its head at the most inopportune moment.

Zolf swallowed thickly, but forced himself to stand strong still. The faster he got all of this taken care of, the sooner he could return to his quarters at Briggs, lock the door, and take suppressants to knock himself out for the rest of this issue. Edward’s eyes were determined as he adjusted his footing but Zolf forced a sneer onto his face.

“‘I got him!” That’s what you’re thinking, right?” he found himself saying as he lowered his slashed hand. “The “courage to kill” is a respectable policy… but actually following it on the battlefield is just handing your opponent an opening.”

Edward’s eyes widened as Zolf shifted. “Lucky for me, you didn’t take your chance to finish me off,” he continued, “That naïveté, that soft nature… not even considering that I might have another philosopher’s sone!”

He felt his stomach lurch as he forced the round stone up into his throat. Gods that was more uncomfortable than normal. He needed to finish this quickly and get the hell out even quicker.

“That sense of mercy’s going to get you into a lot of trouble,” he added as he dropped the stone from his lips into his open palm.

As soon as it hit the array, red, Alchemic sparks lit up around them. Edward staggered back, eyes wide for a moment, and arms crossed in front of him in order to act as some sort of protection from whatever blast was coming.

Zolf wasn’t stupid enough to kill the boy and then walk out, though.

And his less than stable side— the side that rejected what he was with his entire being because what _self-respecting_ man _was born a bottom rung whore for Alphas, disgraceful boy!_ — hissed that it would be better to die here than suffer from _further_ humiliation when he walked out among the Presented Alphas and Betas of Briggs as an Omega who hadn’t had a heat off suppressants in years.

Zolf brought the entire building down on top of them, the haze of heat clouding his mind as Edward screamed. A hysterical laugh was the only thing that left his own lips as the two of them and the Chimeras plummeted down, down, down…

.:.:.:.:.

Zolf bit back a groan as he came back from the dark claws of unconsciousness, finding himself cadged under the ruble of the building as the pounding ache in his abdomen demanded his attention— a hazy feeling settling over him. He ignored the pain, of course as he felt around for the Philosopher's stone. He wasn’t majorly injured, he wouldn't need to use it to heal himself at least. His hand grasped the round stone when he located it, rolling it into his palm and holding it there with his thumb before he adjusted his position. His hand sparked and he pressed it to the ruble above him, blasting it to pieces and slowly climbing out of the mess when he could. The voices that were talking nearby stopped and Zolf glanced over to the direction they were coming from.

The Chimeras were both leaning over Edward, who looked far worse than any of them there. The boy was pale, bloody, and— was that a steel beam sticking out from his side?

He felt something twist in his partially haze-addled mind— goddamn, was his body so fucked the maternal instincts that were _supposed_ to follow after giving birth had surfaced?— and he slowly walked over. He kept his gaze unreadable, ignoring how the Lion stiffened when he got close.

Edward’s eyes filled with pained hate as he saw him enter his vision. 

“Pull the beam from his stomach,” Zolf ordered softly. Darius startled, looking a bit uncomfortable as he looked up at him.

“Won’t that kill him, sir? He’ll die from blood loss,” he pointed out and Zolf rolled his eyes.

“If I couldn’t use alchemy to force the body to close a wound or disable an organ’s functions,” he said slowly, as if he was describing a task to a child. “Then I would have been knocked up a while ago. Quickly now, he’ll die if we wait any longer."

Edward’s eyes didn’t change, but there was a look of determination in them as Heinkel shifted, but nodded. The Lion reached down, grasping the steel beam as the boy steeled himself for the pain that was sure to follow.

“Do it,” he uttered and Heinkel looked to Zolf. Zolf nodded and the Lion pulled. The scream that left the boy was gut-wrenching to Zolf’s Omega side and he moved forwards, Philosopher’s Stone in hand, but Edward knocked him away when he reached for the wound. 

He tried to keep the instinctual hurt from his face, though he wasn’t sure with how well it worked as Edward clapped his hands and pressed them to the gaping wound. Alchemic sparks flew once again as he forced the wound closed before the blonde slumped back, gasping for breath and certainly still in pain.

“A temporary fix,” Zolf told the two Chimeras as Edward slowly came back. “He needs a real doctor if he won't accept my help.”

Zolf paused, lifting his injured hand to sniff the wist of the limb. “And I need a fucking sedative.”

Heinkel shifted a bit, standing slowly and motioning to Darius. The Gorilla Chimera grunted but lifted the half-conscious teenager onto the Lion Chimera’s back. Edward’s face planted right into his mane and Zolf barely hid a snort as Edward managed to _complain_ about getting a face full of mane. At least it was soft.

Zolf stood slowly, shoving his hands into his pockets and stubbornly ignoring the ache in his gut.

The scents of Alphas stories above them drifted down to Zolf, and he shoved his unease aside, walking off with the silent command for the Chimeras to follow. They did as the haze settled over him again, now that Edward (a child, his biological presentation insisted. And Omegas _helped_ children) wasn't in immediate threat of death.

A muffled comment pulled him from his thoughts, and he glanced back at Heinkel and Edward.

“Pardon?” He asked, the Alchemist raising a brow as Edward lifted his head a bit, glaring out at him.

“Why...?” He grunted and Zolf didn’t bother asking him to elaborate.

Instead, he shrugged. “I don’t expect a non-presenting person to understand,” He grunted choosing not to answer the 'why did you help' portion of the word and instead focusing on the 'why did you fall with us' part. “But I would rather have died or defect than be humiliated further with the Briggs Soldiers. The easiest way would be by bringing the whole damn building down.”

He paused, pursing his lips. Now that he thought about it, all of the Homunculi would be classified as “Alphas” as well— Wait, was that why he was being kept around? 

_'What other reason is there to keep a whore around?'_ an internal voice hissed and he growled lowly at the thought. He had lasted this long without that bastard of a father’s opinions encroaching too much and wavering his resolve, he could continue to do so in a full-blown heat.

“Humil… iated…?” Edward mumbled and Zolf sighed again. 

“Forget what I said, Fullmetal, you’ll understand when you’re eighteen,” he told the blonde, waving his hand loftily as he walked on.

The two Chimeras behind him had no choice but to follow.

.:.:.:.:.

Zolf’s normally kept-under-wraps temper had made a reappearance as he paced the length of the room like a restless animal. 

What kind of _goddamn_ doctor didn’t have suppressants? 

He had at best one more day before the full-blown heat hit him and his goddamn instincts wouldn’t let him fucking leave Edward _fucking_ Elric. _And_ he had no idea what the presentations of either of the Chimeras. 

Once they had found a hospital that they could bribe, Darius had taken off to withdraw money from Edward’s bank account, which had tipped the Military off to where they were, and Zolf had somehow found himself under Heinkel’s arm as they made an escape. He had meant to leave them— or kill them— after Fullmetal got treated, but that didn’t happen, as the pre-heat haze settled back across his mind before they had been forced to escape. 

Then Greed had come along and started some sort of drama that Zolf didn’t catch because he was too busy keeping away from the possible Alphas that were Darius and Heinkel. He did catch that Greed had joined Edward’s group before the haze settled fully and made the world fuzzy and out of focus.

Pre-Heat was and would always be a bitch.

So now he was stuck with Edward’s group, in the Rockbell Family Home, on constant watch under Heinkel’s eye— or Greed’s if the Homunculus felt it in his heart of hearts to help Edward.

Why did they even bother keeping him alive when they knew he could betray them at any second, though? 

Zolf had no idea and he could hardly think straight with the weight of going into heat around _them_ pressing in on him. He was certainly _not_ on the edge of a mental breakdown. 

Hormones he had argued internally. He didn’t have anything to control the first heat off of suppressants in close to eight years, so his hormones were going haywire, he argued with himself. Once his mind had settled he would kill the Chimeras and drag Edward back to Central. 

But the slow realization that after the Promised Day he might end up being used as a breeding whore for the Homunculi was eating at him. Being hissed and sneered at him with a voice that sounded too much like his bastard father.

The nervousness and unease that came with being an unclaimed, unstable Omega was starting to settle in as he paced the room he had been put in. Precautions had been put in place, of course. They would have been stupid to not have. His hand would heal without a problem, but it was currently wrapped in tight bandages so that the arrays couldn’t connect. That hardly mattered, of course, with the Philosopher’s Stone back in his stomach, but with how much it had pained him during his pre-heat, he wasn’t exactly keen on finding out if it was the same now. Besides, he wouldn’t have been able to do Alchemy even if he was up to doing so and attempting an escape, his mind was too muddled for the calculations and focus needed for an escape.

(He wasn’t. He knew better than to try anything like making an escape in his current state.)

“Stop pacing, Mister Kimblee,” Heinkel uttered from where he was reading by the door. Zolf slowed his gait but didn't stop, scowling a bit.

“What was your classification?” he asked instead, refusing to sit or stand still for him. If he stopped moving, the need would set in and he would not become a cock-hungry whore in front of the _enemy_.

But were they really? If he switched sides now the worst they’d do would toss him back into prison after the Promised day— or have him killed, but besides the point— should they win. The bastard who called himself his father had been worming his words back into his head, certain that when all was said and done Zolf would be nothing more than a means to breed. 

(Did Homunculi breed? He had too many thoughts now, he was losing his edge.)

Heinkel looked up, brows furrowed and eyes narrowed behind his glasses. 

“Why do you ask, sir?” he asked slowly and Zolf huffed a bit.

“Is it not obvious, Heinkel?” he asked, raising a brow, the Chimera grunted, glancing away with a shrug.

“Alpha,” he said before he frowned, realization dawning on him. “Shit.”

“Yes, ‘shit’,” Zolf drawled but didn’t continue the conversation. Heinkel wisely chose not to continue it either, but now the information was out on the table. Zolf suspected that he and Darius suspected after the whole “Humiliation with Briggs soldiers” and asking for suppressants when they met with the doctor who patched Edward up.

He could only hope that nothing happened that was too pressing for the week when he was going to be prone— and quite vulnerable.

.:.:.:.:.

So life decided to fuck him spectacularly. 

Like his pre-heat, Zolf’s full-blown heat hit him fast and hard.

Everything was horrible and he had forgotten how utterly _painful_ full-heats were without suppressants and sedatives. He felt _gross_ with sweat practically covering his curled up form under the blankets. He cursed his biology in his hazed mind, as slick steadily soaked his thighs. The sweet scent of his heat was flooding the room, heavy and oppressive and he hated it. He hated the smell, and the throbbing pain in his abdomen was growing stronger by the moment, the absolute need to be taken was even stronger and— 

And it terrified him.

The intrusive thoughts were back and the hissing warnings from his father were pounding in his ears. 

And it was only morning.

The pounding on the door made him curl deeper into the covers. He wanted to snarl and hiss for who ever was at the door to just go away, but the only thing that escaped his lips was a pitiful and pained whine.

The door opened just a bit before a curse left the person’s lips. It was slammed closed not a moment later. Shouting sounded from beyond the door as he turned onto his other side, back to the door. He clasped his hands together, just for a sense of familiarity as he curled tighter— his knees were practically up to his chin and pressed against his chest now. 

The door was pushed open again and he let out a weak snarl, twisting back to glare at who ever had decided to come into his— Oh. It was just Heinkel.

Oh.

Oh _fuck_.

He instantly was on high alert— well as high as he could be in his heat-induced haze— scrambling back and pressing his back against the wall, putting as much distance between he and Heinkel as possible.

“Wh- of all people to send, they sent _you?”_ He hissed and the blonde just shifted a bit, staying by the now-closed door. He had a tray with a glass of water and a plate of food in hand, but the Chimera’s knuckles were white. Zolf didn’t trust him and he didn’t need to be close up nor have the Lion take his glasses off to know that his pupils were fully blown with arousal. He had dealt with Alphas in his younger days, he knew how to escape and entice them all the same. He knew how they acted.

Still, Zolf pressed back even farther against the wall, hands twitching instinctively even though he _knew_ he was next to defenseless as he was now. 

Shit, was that their plan?

He needed to clear his head and _fast_. He couldn’t allow Fullmetal to pull one over him again, especially not in this way. He was better off dead, but there was nothing in the room he could use to— No. He could always bite his tongue off. Die that way, he wasn’t afraid of death. He could do it.

Just as he was contemplating this, Heinkel had crossed the room and set the tray on the desk. Zolf recoiled, but the Lion backed away, hands up in a peace offering sort of gesture. 

“The others don’t want you dying,” he said simply. “We sent Darius to check on you when you weren’t heard moving.”

“So he sent… for you?” Zolf asked, panting softly as he cringed just a bit as another spike of pain shot through his abdomen. The smallest whimper escaped him, and he bit down on his lip, but it was obvious that the Lion had heard him when the blonde’s posture stiffened and he shifted again.

Zolf had to commend the Chimera for keeping his sanity, but it was bound to snap eventually if he _stuck around._

Heinkel swallowed. “Yes.”

“Why?”

The Lion shrugged and Zolf hissed lowly. Not a good enough answer and it didn’t tell him anything about what was going on outside of the room— not that anything ever did nowadays. Still, it would be nice to know if he was going to die while he was in this state. Once upon a time, six years ago, Zolf would have been able to stand a chance in a normal state against Heinkel, but six years of prison and a full-heat would make him no match for the Chimera.

Heinkel was broader, much more muscular, and undoubtedly stronger than he would ever be— and he was a Chimera. Zolf couldn’t help it as his gaze traveled down… his mouth went dry.

His scent was clearly getting to the Chimera, and Zolf’s body ached, just by seeing a part of what the Alpha had in size. Zolf quickly turned from the Chimera, scowling at his own weakness as Heinkel slowly backed towards the door, as if he was worried about startling him.

“If you need anything, sir, just- just yell.”

The Chimera fled the room and Zolf allowed his shoulders to relax. But the lack of Alpha Chimera only made the ache deep in his abdomen grow stronger. His body needed to be bred, but Zolf would not give in. He reached over the edge of the bed, grabbing the water and knocking it back before he set the glass back.

He would not give in, even if the Lion was well-built and made the heat in his abdomen flare. Male Omegas would settle with either man or woman, Zolf knew, but his tastes were solely men— and by god, Heinkel was quite _literally_ everything a prime Alpha was supposed to be in looks, and personality. Protective and strong, possibly decent with children, if his interactions with Fullmetal were anything to go by.

The alchemist stubbornly flopped back down on the mattress and curled back up as he shoved his internal musings aside.

He briefly wondered when he started thinking like a stubborn teen with a schoolyard crush instead of the Mad Bomber that he was.

The thoughts vanished into nothing as he drifted off into a fitful sleep.

**Notes for the Chapter:**

> NSFW next chapter. Also OOC Kimblee? More likely than you think.


	2. Chapter 2 *NSFW*

**Notes for the Chapter:**

> And here's the smut because I break things into chapters and now this is a whole ass AU so like yeet, I guess

The next few mornings were no better than the first. In fact, Zolf would wager that when he woke on the afternoon of the fourth day, his heat was even _worse_.

The fire in his abdomen raged even hotter than before. Somewhere in the night, he had peeled off the outer layers of his clothes, leaving him in his briefs only but it was still excruciatingly hot.   
He had entered his peak-heat. Where his body was more sensitive, and the risk for brats was higher.

Zolf laid curled up on his side, panting heavily as he squirmed in the sheets. He cursed his biology, not for the first time, as soft whimpers and pained whines escaped him.

He was not so far gone, however, that he could not come to a final decision on what his next plan was. It wasn’t the best choice, but it was one that would allow him to at least keep a semblance of dignity intact when the end came.

Fullmetal wasn’t planning to kill him, and while he was (almost) certain that the Homunculi were still going to win, he would rather die with humanity than become a breeding _bitch_ for them when this was all over. He was almost certain that he would end up like that— he was human and expendable, lower than they were. Lower than most others of the human race by _default_ because of his Presentation.

(He might just get killed in the end, but he didn’t want to risk the thought of… the _other_ option.)

The only problem was getting the truce.

That problem was solved when the door opened just slightly again. A sharp curse from Greed made Zolf shift, a quiet whine escaping him. Like Darius had done the previous days, Greed turned and called for Heinkel. In truth, Zolf had no idea why they kept calling for Heinkel, but by god was he going to take advantage of it.

Darius, he learned, was a Beta, but wasn’t comfortable enough in the presence of an unmated, unmarked Omega in heat. Edward still hadn’t presented, he would when he turned eighteen so as of now he was unaffected by Zolf’s heat. Greed— as much as he would have certainly wanted to stake claim to Zolf as an Alpha— held himself back. Perhaps his vessel had control still? Maybe his vessel had been married. Zolf _highly_ doubted that the others would have held him back otherwise.

That left Heinkel who was certainly using every ounce of control to keep himself from diving into his Alpha instincts. 

Zolf, on the other hand, could barely do the same whenever the blonde came in. 

The Chimera would come in at varying points of the day to check in on him, and every single time, the Alpha’s scent— strong, musky, and like the earth— hazed Zolf’s mind even more than before.

Rationally, Zolf knew the best way to ensure that he wouldn’t be killed on sight by Mustang and his group if and when they met with Fullmetal (they were allies, so why wouldn't they meet again?) would be to have one of the Alphas stake a claim to him— It was genetic instinct, no Omega would risk their (admittedly little) worth by turning a hand against their Alpha unless it was dire. Zolf had little pride in being an Omega, but he prided himself for at least knowing he didn't have _that_ much of a resolve to betray the first Alpha who claimed him. Besides, he would still get to see the outcome, his goal wasn't changing and he wasn't betraying his beliefs, as skewed as they were.

(And rationally, Zolf knew that when he looked back on this point in his life he would become irritated with himself with such a half-baked plan, but rationality was slowly being eaten away by the burning need between his legs.)

So when Heinkel stepped into the room, practically shoving a grumbling Greed to the side, Zolf stat up, the sheets pooling around his waist. He saw, he heard, Heinkel swallow, adam’s apple bobbing just slightly. The Alpha averted his eyes, gripping the tray again with that white-knuckled grip of his, but his foot moved to close the door. 

Zolf’s gaze never wavered from him, eyes hazy and half-lidded, as the Lion moved to set the tray on the desk by the bed. He reached out, grabbing him by the wrist as he started to leave, startling the Chimera. 

It was slow, hesitant, but Heinkel met his eyes. Golden irises met pale silver irises, pupils blown wide and full of need. The Chimera swallowed thickly again.

“Please,” Zolf breathed and that was all that was needed for the blonde to _snap_.

The blankets and remaining sheets were all but thrown to the side as Heinkel tore his shirt off and over his head. It went discarded over the edge of the bed and Zolf whined under him when he climbed over top of him, knees settled on either side of his waist. Zolf squirmed when he felt Heinkel bury his face in the crook of his neck, close to where his primary scent gland was. The Chimera inhaled deeply, making Zolf whine a bit as heat flooded his insides and his cheeks.

A low growl left the other man and he stiffened, the noise going directly to his core.

“You have never been claimed,” Heinkel rumbled against his skin and Zolf’s breath hitched, feeling his rationality give way as he nodded. The Chimera rumbled lowly again, tongue tracing the gland and Zolf shuddered, hands twisting in the sheets.

“You want this?” he breathed and Zolf nodded again.

“Please,” he begged softly, pressing his cheek up against the Lion’s own. He could feel the Lion’s clothed arousal pressing up against his own and he needed him. Heinkel was still seeming hesitant, despite his plea, so Zolf shifted a bit, bearing his neck to the Lion above him.

 _“Please,”_ He begged again. _“Alpha.”_

A low growl left the Lion and a Zolf let out a cry of pleasure when his teeth dug into his skin. Even as a human, Heinkel’s teeth were sharp, sharper than a normal Alpha’s would have been. He hadn’t bitten the scent gland, but by god, he was so close. 

Zolf whined softly again, breath hitching as the Chimera pressed his hips down against his, growling lowly against his neck and rocking his hips. He weakly raised his hips to meet his, hands gripping and twisting in the sheets before Heinkel sat up, swiping his tongue across his lips. Blood slowly dripped from the bite on Zolf’s neck as he panted, gazing up at the Alpha.

Heinkel lifted himself back up and off of Zolf, much to the Omega’s displeasure, but it was instantly satiated as the larger man cut off his whine with a low growl while he worked him out of his briefs. 

The Lion’s breath hitched and his fingers ghosted along his thighs. “By god you’re _slick_ ,” he rumbled and Zolf let out a breathy laugh, shifting his legs.

Heinkel rumbled a bit and before he knew it, his shoulders were thrown over the blonde’s shoulders and a mewl of surprise was escaping him as the Alpha’s tongue plunged into him.

 _“Ooh!!”_ he gasped, squirming and pressing his hips against the Lion, head tilted back. A low rumble of amusement left the Chimera as his hands gripped his thighs, tongue twisting and thrusting deeper inside of him. Zolf’s back arched and a breathy moan passed his lips, then a cry as Heinkel’s tongue was suddenly replaced with two fingers, curling and pressing against his prostate.

“Heinkel—!!” he cried, head tossing back and Heinkel rumbled.

“Like that, sir?” he practically purred, licking his lips and Zolf nodded, moaning as his fingers thrust in and out of him, curling and pressing up against his prostate every so often. 

He squirmed and twisted, hips pressing back as the coil that had already building up in his stomach tightened further and further. He wasn’t even sure what he was saying anymore, pleas escaping his lips between moans and gasps.

Heinkel had moved back to his throat, rumbling and nipping the skin as he pushed a third finger inside of him. Zolf arched, head tossed back as moans and begs passed his lips— the Lion’s fingers curling and thrusting deep inside of him.

( “Please— please, please— o-OOH-!! _Oooh!!_ H-Heinkel- _Alpha_ \- pl-pleeease—!!”

“Hmph, so loud, sir. What will Fullmetal think?” )

The coil was getting tighter, Zolf’s hips pressing back harder against his fingers as he was stretched. Heinkel rumbling and chuckling against his throat, his other hand trailing featherlight touches across his skin. 

“Good job, sir,” he rumbled, “So tight, but so pliable for me, aren’t you?”

“Y-yes— Ye-esss—“ he whined back, “P-pleaase—“

He was so close, he was almost there, by god, he could come just from this alone—

A sharp whine escaped him when Heinkel pulled his fingers back. 

“Patience, sir,” he breathed, nipping his throat before he flipped him over. Zolf gasped, shifting a bit before gasping again when hands grabbed his hips and pushed them upwards so his ass was propped up by his knees.

The perfect presentation position for an Omega.

A low rumble left Heinkel again and Zolf whined softly in return. Every time the Alpha Lion rumbled or growled, the noise sent tremors down his spine.

The sound of clothing dropping to the floor made Zolf’s breath hitch, and more slick dripped down his legs. A hand on his ass made him whimper a bit. Gods he needed Heinkel inside of him _yesterday_. What was he waiting for?

He voiced his impatience with another whine, but got a smack on his thighs in return, making him jolt with a surprised moan. 

“Oh,” Heinkel’s voice breathed next to his ear, a heavy weight pressing against his back. “You like that, sir?” 

Zolf swallowed, nodding a bit. The Lion chuckled.

“I’ll keep that in mind for next time,” he rumbled, running his tongue against the shell of his ear. A hand ghosted across his thighs, wiping up slick before a sharp hiss of pleasure sounded and Zolf _knew_ that the Chimera was using his own slick to lube his cock. And that fact made him shudder. Another hand rested on his hip as the weight on his back adjusted. 

“I’m going to fuck you now,” Heinkel rumbled, teeth biting down on his ear and tugging lightly. “As a reward for being a good little Omega.”

His breath hitched and he whined, shifting his knees and pressing back against him. The Chimera rumbled with an amused laugh, squeezing his hips.

(So much for not breaking down like a cock-hungry whore, Zolf would later grumble about.)

He started pushing into him and Zolf’s breath hitched, then caught in his throat as his entrance _stretched_.

_“Oohh—!!”_

Another rumbling laugh escaped the Lion above him, hands tightening their grip on his hips as the Alpha slowly pressed deeper into him. It was becoming increasingly obvious how _large_ the blonde was, Zolf thought hazily before his thoughts dissipated with a cry of pleasure spilling from his throat when Heinkel shoved deeper into him.

By god, the man wasn’t even bottomed out yet and Zolf felt like he was being split open, and he _loved_ it. His eyes had since begun to roll back, hands clenching the sheets tightly and hips weakly pressing back.

“Sweet god,” Heinkel breathed in his ear, pressing deeper and deeper into him. “So tight, _sir_ , I might just come from this alone.”

His tone was deep, thick with lust, and teasing as he adjusted his grip on his hips. Zolf opened his mouth to say something in return, only for a _wail_ of pleasure to escape him when Heinkel shoved all the way into him.

Zolf’s eyes rolled back and his back arched as the Alpha stilled, a hand gently rubbing his hip while another snaked around to his front. Zolf thought he was going to touch him, only to gasp as his hand pressed gently against his lower abdomen and a low, rumbling chuckle escaped Heinkel.

“Thought so,” he rumbled before he reached up and gently untangled one of Zolf’s hands from the sheets. He guided it down, pressing it against his stomach and he gasped.

“Can you feel me inside you, sir?” Heinkel _crooned_ , “You’re so _tight_.”

Zolf moaned, shuddering and weakly rubbing and pressing the budge in his stomach. His gaunt form from prison certainly didn’t help hide anything, but the alchemist found that he didn’t care about that. Heinkel was huge and he felt _good_ buried so deep inside of him. 

The Lion rumbled lowly, hand over top of his own before he slowly drew himself out of him. He whined in protest, before he was rocked forwards with a sudden cry of pleasure when Heinkel shoved back into him. 

“Fuck,” he heard the other breathe as he arched again. And then he was moving and Zolf couldn’t do anything but moan and gasp with each thrust, the occasional sob or wail escaping him when he pressed deeper at the right angle. The Lion was murmuring into his ear, breathing praises, or biting into his neck and shoulders. It felt as if Zolf’s language consisted of _‘Harder, more, please, Heinkel—!!’_ as he was fucked into the mattress, his other hand gripping and clawing at the sheets while the other remained firmly pressed against his gut by Heinkel’s larger one— feeling the Chrimera’s member as it was thrust in and out of him. His own was painfully hard, and dripping with pre, but he knew better than to come before he was allowed.

He didn’t have to worry about that, though as Heinkel nipped his ear. “You’re tightening so much,” he rumbled. “Need to come? You can, go ahead, sir.”

Zolf’s breath stuttered and he gripped the sheets even tighter as Heinkel shoved into him, the coil in his stomach snapping and he came with a sob of pleasure. Heinkel didn’t let up, though, fucking him through his orgasm with a rumbling groan of pleasure. 

“Good, so good,” the Lion purred, hand trailing from his abdomen to his member and taking him in hand. Zolf’s hips jerked, pressing into the larger man’s hand with a high-pitched whine, and then he was coming again, hands twisting and gripping onto the sheets, moaning and gasping. Heinkel rumbled something that sounded very close to “I’m staking claim to you, now” and Zolf just mewled and pressed his hips back to meet his thrusts again.

The Lion’s hand was still slowly jerking him off and a wail of pleasure escaped him when he sunk his teeth into the back of his neck— officially claiming the alchemist Omega as his as he shoved all the way into him to the hilt and came with a muffled roar that sent shudders of pleasure down Zolf’s spine.

There were a few more moments of gasping pleasure before Heinkel slowly let go of his neck, tongue tracking the bite marks and lapping the blood up as Zolf slumped bonelessly into the bed, face down with a low groan. The Alpha rumbled gently, hand stroking his side in a calming motion. Slowly, the Chimera pulled out from him, making him whine lowly at the loss as come dripped from his entrance and down his legs. Heinkel flopped ungracefully down beside him, one arm wrapped around his waist as he lay on his side. Zolf shifted, turning his head to face Heinkel, eyes half-lidded and hazy still.

His mind wasn’t much better, still muddled with the effects of his heat, but also with the aftershocks of pleasure as he shifted. He nestled against the larger man's— against the alpha, _his_ alpha, as dictated by the mark on his neck— chest. He briefly heard Heinkel rumble soothingly, pulling him close against him. 

He shuddered, as the blonde buried his face against his neck, breathing in his scent with a possessive, yet pleasant growl. A pleased and happy haze started to settle over Zolf’s mind, effectively pushing away the thought of irritation at giving in to his weakness so quickly. 

But he had insurance now. Heinkel was in alliance with Fullmetal, and Zolf was now Heinkel’s— he would be a fool to ever turn on his Alpha.

**Notes for the Chapter:**

> I’m basing the whole alpha-knot situation based on the fact that Heinkel is a Lion, and Lion’s do not have knots. Also Lions mate up to 100 times over a span of four days when first mated. So. Uh. Rip Rat Man ™
> 
> Also this *is* Mangaverse Kimblee because I really just don’t like the blue eyes that they gave him? Manga gave him pale eyes and a red tie and we stan that.
> 
> Edit: I was told that zolf’s eyes are silver not lilac. I am. Blind.


	3. Chapter 3

**Notes for the Chapter:**

> Edit: Obligatory final chapter
> 
> And now I'm trying out Heinkel's POV. I don't really see too much of him around, but his mustache is perfect and Bradley wishes he could be him.
> 
> Oh right: TW for Prostitution (because life is hard. Support Sex Workers! They're people too!)

Kimblee was, for lack of a better term, incapacitated in his current state. There was no better way to say it, especially after a few more rounds. And as much as he would like to stay in bed and fuck the now-former (he supposed) Major into the mattress when he woke back up, he did have to go back down to talk with Edward, Darius, and Greed.

Once he was sure that the Alchemist was in a deep enough sleep to not be disturbed once he left, the Chimera carefully and slowly untangled himself from the smaller man. He froze as an irritated whine left Kimblee, but relaxed when he just turned onto his side, curling up. He let out a sigh, standing and tugging his clothes on slowly. As soon as he was dressed, he lifted the blankets and sheets up, covering the sleeping Alchemist with a silent sigh.

Part of him, the part of him that was dictated by his biological presentation, was extremely reluctant to leave Kimblee— his mate, his Omega— like this. But the logical side of him grimaced and knew that he did have to report back to the others. Kimblee was, at best, a loose cannon. At worse, he would go against the genetic instinct and kill them all. 

He hoped that the “at best” changed to “on their side” but he wasn’t holding his breath, he realized as he quietly opened the door and slipped out of the room. He walked down the hall towards the upstairs bathroom, cleaning himself off, and then down the stairs rubbing the back of his neck. He’d return to clean Kimblee off after he met with the others.

The basement door opened and Greed peered up with a large grin on his face. “Nice,” he said, giving him a thumbs up and Heinkel rolled his eyes as he entered in with Edward, who looked flushed and embarrassed. Darius followed last, closing the door behind him looking not much better. 

“Who knew that Mister Kimblee was an Omega?” the Gorilla Chimera asked as the four of them moved to the Rockbell kitchen. Edward still looked quite red in the face while he sat down at the table as Greed cackled a bit.

“I mean, he has a nice ass, so it makes sense,” the Homunculus noted and Heinkel felt a growl build up low in his throat. Darius snorted.

“I thought you said you hadn’t met him before,” he commented and Greed shrugged. 

“Don’t mean I wasn’t checking him out earlier, bud,” he said back with a grin as he sat down and leaned back. Darius sighed and shook his head as Heinkel glared. 

Edward cleared his throat, fighting down his blush.

“So… ah, what do we do with him?” he asked, and not for the first time since they had dragged the Alchemist from Briggs to Resenbol. Honestly, Heinkel could smell the Alchemist’s pre-heat’s beginnings since they first met him, and it was both startling and amazing that the man had managed to hold off on going into a full-heat while they were on the road— even if his pre-heat had muddled his senses and memory. 

Darius looked to Heinkel, who stared blankly back. 

“Well?” Greed prompted, grinning still. “You’re the guys who fucked him, Lion-Man, what’s your input?”

So eloquent.

Heinkel ran a hand down his face. 

“Right now, it’s a hard call,” he said finally, sighing. “Technically, he should be harmless. It pains an Omega and breaks their pride to turn their own hand against their Alpha, something deep in their biological makeup or something like that. If there's one thing Kimblee holds in high standing, it's his pride.”

Darius rubbed his chin, nodding. “But, if they’re used to breaking away and breaking claims, it would certainly be easier, we can’t actually expect that to hold Mister Kimblee, right? After his heat passes, he’ll probably be back to killing us.”

Greed crossed his arms, raising a brow, leaning back as Edward made a face. “Just knock ‘im up then,” the Homunculus suggested, “Soon as he knows he’s got a brat in ‘im, he’d be against fightin’ right?” 

Heinkel instantly bristled, glaring and feeling his Lion-self start to resurface— teeth and nails elongating first into fangs and claws. Darius grabbed his arm tightly to hold him back, eyes serious.

“Out of the question,” the other Chimera told Greed as Heinkel forced himself back into his Human Form. “If it’s on the table _at all,_ it’s last resort.”

Greed scoffed but relented as Heinkel glared still. 

“Besides,” he said, shoulders slowly lowering as he frowned. “It was his first time being marked and claimed.”

That made both Greed and Darius startle, though Edward tilted his head and seemed to be having trouble following along. Surely the kid had been taught about the Biological Presentation System in school? If he didn't he really didn't look forward to educating the young alchemist.

“You’re joking,” Greed asked, eyes wide and Heinkel nodded. "Good god, how the fuck did he manage _that?_ The Military is _full_ of Alphas and Betas." 

“He doesn’t bear any other mark than mine,” he said, shaking his head. “Nor were there any other lingering scents. He wouldn’t have had any practice breaking down a bond.”

“I wouldn’t put it past Kimblee, though,” Edward grumbled. “Who knows, he could have just healed the marks with a Philosopher’s Stone.”

Heinkel sighed, rubbing his eyes behind his glasses.

“You’re right about the first part,” he said. “But the second part I don’t think so. He’s got plenty of scars and Claim Marks scar, if he hasn’t removed the others, I don’t think he’d remove those. But if you choose to leave him somewhere I physically can’t help you do anything to help you do it.”

Greed made a face at that, brows furrowed and lips drawn into a confused frown. “Why? Alphas leave their Omegas behind all the time, hell, _I_ did it in my, ah, past. Or whatever the memories say.” He tapped the side of his head, grinning again.

Heinkel frowned, arms crossing across his chest as he shifted a bit, then sighed and lowered his head. “Call me a fool, but it feels wrong.”

Edward scowled. “In case you forgot, he did try and kill us all by bringing that building down, plus, he’s working with the enemy,” he snapped. “Who cares if it feels wrong?”

“Don’t you think I don’t know that!” Heinkel snarled, teeth bared and back to being fangs again. Edward jumped a bit, his eyes hard and lips drawn into a deeper scowl and hands moved to clap together in defense.

“You haven’t presented yet, Fullmetal,” Darius said, trying to calm the situation down by placing a hand on his friend’s shoulder. “An Alpha’s innate instinct is to protect their mate, be it Omega, Beta, or another Alpha. Omegas are incredibly rare nowadays, the instinct is heightened even more because of the lack of them around. We can’t really fault Heinkel for being reluctant.”

Edward still looked pissed but Heinkel pulled from Darius, turning and walking out of the room, ignoring the questioning call after him. 

He certainly knew that what Edward and Greed were saying and suggesting were right, Kimblee was dangerous and would turn against them in a blink of an eye, but…

Heinkel just couldn’t. 

He couldn’t and he wasn’t sure if that was a good thing or a bad thing.

.:.:.:.:.

Two days later, Kimblee’s heat broke and he slept undisturbed through the night.

Heinkel sighed, rubbing his forehead as he climbed the stairs slowly. It was far too early in the morning for this, he had decided, with 'this' being _another_ argument-filled meeting with Darius trying to placate both parties while Greed made obscene comments. In the end, he (once again) left without explanation while Fullmetal yelled about Kimblee being dangerous, and Greed being generally unhelpful.

The Lion sighed as he pushed the door to Kimblee’s room open, rubbing the back of his neck again before he blinked.

The raven-haired man was awake and propped up on his elbows and on his stomach, running his fingers over the bite marks across his shoulders. He glanced over when Heinkel shut the door, dropping his arm back onto the bed.

“So, what’s the verdict?” He asked loftily, voice quite rough and raw from the past week as he lowered back down to rest his head on his arms. “You’re not exactly quiet down there with all the yelling.”

Heinkel snorted, moving over to the bed and sitting down on the edge. 

“No verdict yet,” he told him and the (perhaps) former Major hummed, turning his head from him.

“You’re a horrible bedmate,” Kimblee said after a moment and Heinkel blinked. Prior to Claiming him, Heinkel would have thought that was an actual piece of criticism from a higher officer, but for some reason, it felt as if the other man was using snark, insults, and sarcasm to deflect fear.

Huh. 

He wondered where that idea came from.

Shaking his head, he pulled his shirt off and over his head, pants following soon after as he slipped into the bed next to Kimblee. “Sorry.”

Kimblee just snorted, but turned onto his side and nestled against him with a sigh.

“Horrible,” he drawled again, “What Alpha stakes a claim and then leaves as soon as he can?”

Heinkel rolled his eyes, just barely taking note of the change in Kimblee’s voice. “All due respect, Kimblee, sir,” he said, “We're not alone in this house, _and_ you are considered an enemy still.”

Kimblee frowned, brows furrowing before he hummed, shrugging and moving up onto his chest, and resting his head there.

“I know,” he said simply after he got situated. “About that… ya know that I can’t go against instincts, right?”

This time Heinkel did take note of the change in his voice. His brow furrowed.

“What?”

That just made Kimblee sigh. “I mean ‘m not gonna betray ya.”

Heinkel shook his head, sitting up slightly on his elbows.

“Not what I meant,” he said, “Your accent changed.”

Kimblee blinked, brows furrowing a bit as he narrowed his eyes. “Bother’s you then? I can go back. It happens sometimes and I just assumed…” he trailed off before shrugging. "Not a problem, though."

Heinkel huffed a bit, placing a hand on his head and stroking his hair and his stupid flyaways back, making the Alchemist grunt and give him a half-hearted glare as he looked up at him.

“No, just surprised,” he said after a moment, stroking his hair back again. “I thought you were all posh and upper class.”

“Hah! I wouldn’t be an in the Military as an Omega if I was,” Kimblee said after he barked out a laugh. He didn’t elaborate so Heinkel didn’t press as Kimblee rested his head down on his chest. 

“I’m actually surprised you’re so composed right now, I was under the impression that after heat broke it was still a haze,” Heinkel admitted. Kimblee shrugged. 

“Oh, ’m still plenty horny and touch starved, still, Heinkel,” he hummed, and Heinkel raised a brow. Kimblee chuckled a bit at that, lifting his head again.

“I’ve had twenty years to get used to comin’ outta heats,” he said simply. “Gotta learn quickly when you present early.”

That certainly perked Heinkel’s curiosity as he found himself stroking Kimblee’s hair again. “You presented early?”

Kimblee shrugged. “Well, earlier than the upper and middle classes in Amestris, not sure how early that is for Xing.”

Well, that just made him more curious. “Xing?”

Kimblee pressed a hand to his mouth. “Patience,” he huffed, “I’m half and half, born in a slum outside of Central. The lower down on the class system ya get, the sooner the kid presents. Depends on the slum too, how much food’s available and shit like that.”

Heinkel huffed softly back as he moved the bandaged hand from his mouth. “And how old were you?”

Kimblee just gave him a look. “Really?”

“It’s a reasonable question since you’re sharing!” He grumbled and the Alchemist rolled his eyes.

“Fifteen.”

“Shit,” he breathed. “That’s young.”

Kimblee tilted his head. “Is it? I mean, was pretty normal for where I was,” he mused, thinking. “Oh, but unspoken rules ‘bout Omegas were in place. We got a higher number of ‘em and no one wants to deal with bastard pups from teens. No claiming until of age, always pull out, that kinda shit.” 

The raven-haired man shrugged a bit. “At least money gets made. I picked up some rather unsavory work until I could join the Military. Studied Alchemy on the side, joined as soon as I was eighteen.”

“You sold yourself for money,” Heinkel rumbled, brows furrowed. Kimblee’s nonchalant and almost amused attitude melted and then froze over into a shockingly cold expression.

“That bother you, Heinkel?”

“No,” he grunted. “Not in the way you think. Just don’t do it anymore. You don’t have to now.”

“Ahn?” Kimblee raised a brow. “The fuck do you think I am? Ya can’t go around getting fucked for money when there's a claim. It don’t work like that, Hein.”

Heinkel huffed. “Alphas—“

“Are the highest rank, so they can do what they want,” he said, jabbing his finger into his chest with a scowl. “It doesn’t work that way with Omegas. I know there’s not a lotta info since the higher class has mostly Betas and Alphas, and the military is chock full of them. We ain’t like Alphas ’n’ Betas.” 

Heinkel held his hands up in defeat. “I got it, I got it, no need to get huffy.”

_‘But it’s fucking cute.’_

Kimblee just scowled again, settling back down. Heinkel chuckled, gently cupping his cheek and running his thumb across it. The Alchemist whined a bit at that, but leaned into his touch.

“Cute,” he murmured and Kimblee glared, though his eyes were half-closed and it seemed as if exhaustion was taking over again.

Heinkel just laughed. 

Who knew that the terror of Ishval could _do_ cute?

“Hey,” he said softly, making Kimblee huff but lift his head with a raised brow. “Why let me do this?”

He grumbled, but propped himself back up on his elbows, stifling a yawn. “Because like any other Omega, we’d rather prefer to be fucked and Claimed than just fucked. I'm pretty sure that Homunculi don’t claim. Well, Greed maybe, but he’s an outlier. Money’s money, but I don’t plan on goin’ back to pre-military me if I can help it.”

Heinkel hummed. “No betraying us, then?”

“Nope,” he said pushing himself up and rocking back. Heinkel groaned lowly, pressing his head back against the pillow as Kimblee rocked his hips.

“Really? You just said you had control over this,” he huffed. Kimblee only grinned.

“Oh, Heinkel,” he purred, “I’ve had six years without contact with anyone aside from shoves and pushes from inmates and guards. Let me have this.”

Heinkel just let out a halfhearted huff, but reached up, grasping his hips with one hand and tugging his briefs off with the other. “You’re lucky that I’m a Chimera Alpha with so much stamina, you ass.”

“Tsk, the _attitude_.”

“Shut up so I can fuck you.”

**Notes for the Chapter:**

> There are so many headcanons for Kimblee’s past and I personally like the idea of Local Slum Kid Working His Way Up Goes Mad With Power To Spite His Dad and Also God Probably. Hence the differentiating accents. Also have y'all seen Zolf? He's at least a little bit Xingese (or Drachman, I chose Xing).
> 
> Also, also; Is Zolf now shortening Heinkel’s name? yes. Yes, he is. 
> 
> And a smaller note: This is my own interpretation of the ABO dynamic. Because originally this was literally just going to be a pwp oneshot but now here i am.
> 
> Edit: i forgot that this was going to be the last chapter before I wrote an actual fic for this, but yeah, this is the last chapter so look for "Turning Tides" if you want HeinKim I guess

**Author's Note:**

> OOC Kimblee, more likely than you think! But It's not super-duper off the mark, I don't feel? + the whole Omega Instincts thing. Whatever. The brain worm demands writing sacrifice.
> 
> It always sat weirdly with me that Kimblee was straight up trying to kill Ed, since his bosses needed the sacrifices and all that, but like eh. I fix.


End file.
